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Biomedical subjects

F Lutz

Publications and source records attributed to F Lutz.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Prophylaxis pastes--the new abrasive Perlit compared to conventional polishing substances].

Perlit is a new dental abrasive, based on volcanic silica. It has a flat, irregular disc-shaped structure which fractures readily in use. Individual discs tend to become oriented parallel to the tooth surface during use while the rough edges also become rounded. A Perlit-based prophylactic paste thus produces polished surfaces although it also has excellent cleaning properties on both enamel and dentin when used with either rubber polishing cups or bristle brushes. The Perlit-based prophy paste, Cleanic, yielded the best results when compared to other prophy pastes during laboratory test scored with the Prophylaxis Paste Index (PPI: Cleaning efficacy: [Abrasivity x Surface roughness]). Consequently, Perlit-based prophy pastes can be used initially as cleaning pastes and the same portion will subsequently polish the dental surfaces as well. Thus Perlit nullifies the rule that an efficient cleaning paste will be abrasive and must produce a roughened dental surface.

Aluminum Oxide↗
PubMed1994

Pore-forming Pseudomonas aeruginosa cytotoxin.

Pseudomonas aeruginosa procytotoxin protein is processed C-terminally during bacterial autolysis to generate the active 29-kDa cytotoxin molecule. Binding to target cell membranes is dependent upon Cys23 and Cys215 and a domain flanked to Cys215. On rabbit erythrocytes, cytotoxin binds to a 28-kDa peptide of a glycoprotein, its N-terminus shows high homology to channel integral membrane protein CHIP28. At concentrations of more than 3 x 10(-9) M, cytotoxin increases plasma membrane permeability of most eucaryotic cells investigated. The role of cytotoxin in the formation of pores with a diameter of 2 nm on mammalian cells is discussed. The cytotoxin effects are coordinated with other pseudomonal products and the resultant concept of pathogenesis is presented.

Amino Acid Sequence↗
PubMed1994

Changes in rabbit corneal epithelial membrane permeability caused by locally applied Pseudomonas aeruginosa cytotoxin: a microfluorometric examination in vivo.

The effects of a pore-forming protein from Pseudomonas aeruginosa on the rabbit cornea were tested in vivo by measuring intraepithelial carboxyfluorescein accumulation. Carboxyfluorescein diacetate and subsequently the P. aeruginosa cytotoxin were applied by means of contact lenses with a spherical cavity on the concave surface. This allowed the application of defined concentrations of carboxyfluorescein diacetate and cytotoxin on a defined area of the corneal epithelium. Starting at 0.5 microM, cytotoxin increased the epithelial cell membrane permeability for the intracellular carboxyfluorescein within 1 min. At higher concentrations cells were shed from the epithelium. Corresponding morphological changes of the cellular structure of the corneal epithelium were observed and documented by fluorescence photomicrography. The healing process of toxified corneal epithelium appeared to be complete within 3 days. The data presented here indicate the possible role of cytotoxin-induced changes in epithelial permeability in P. aeruginosa infections. In this context, the role of soft contact lenses as a possible cytotoxin reservoir is discussed.

ADP Ribose Transferases↗
PubMed1994

Wear and marginal adaptation of composite resin inlays.

MOD inlays were made with conventional, coarse hybrid, fine hybrid, and two microfilled composite resins. They were adhesively luted in six extracted human molars for each group and were subjected to longitudinal, in vitro testing. Final wear ranged from 46.8 +/- 18.6 microns for fine hybrid composite resin to 132.0 +/- 39.3 microns for conventional composite resin for the inlays and from 19.3 +/- 6.6 microns for homogeneous microfilled composite resin to 136.3 +/- 65.1 microns for coarse hybrid composite resin on enamel antagonists. The wear of the luting composite resins ranged from 11.2 +/- 11.2 microns to 20.0 +/- 23.6 microns. Marginal adaptation at the beginning of the test exceeded 88.7% of "continuous margin" for all groups in enamel. However, marginal gaps were evident in dentin without dentinal adhesives. Marginal adaptation of the microfilled composite resin inlays deteriorated during loads even when a dentinal adhesive and an inlay primer were used. The margins of the other composite resin inlays remained stable during load application.

Acrylic Resins↗
PubMed1994

Pseudomonas aeruginosa cytotoxin as a pathogenicity factor in a systemic infection of leukopenic mice.

The effect of Pseudomonas aeruginosa cytotoxin was assessed in leukopenic outbred Swiss male mice (20 g) using a high cytotoxin-producing strain (PA158) and its cytotoxin-deficient isogenic mutant (PA114F5) generated by Tn7::Tn5 transposon mutagenesis of PA158. Leukopenia was induced by intraperitoneal (i.p.) administration of cyclophosphamide (150 micrograms/g). Anesthetized mice were infected via a 4 mm incision on the shaved back with 300 CFU/mouse (9 LD50; expected death rate 85%). Precleared mouse cytotoxin-specific heat inactivated rabbit polyclonal antibody (RPA) was administered i.p. (0.2 ml) 24 hr before challenge. Controls received i.p. normal rabbit serum, RPA, cyclophosphamide alone, or a sham procedure. Challenge with the high cytotoxin-producing strain PA158 caused earlier and a significantly greater mortality than that observed with a cytotoxin-deficient strain PA114F5 (P < 0.01). Cytotoxin-specific polyclonal antibody was protective. Pretreatment with antibody decreased the mortality rate following challenge with PA158 from 88.9% to 27.8% (P < 0.01). Pretreatment with antibody decreased the mortality rate following challenge with PA114F5 from 27.8% to 5.6% (P < 0.05). These results demonstrate that P. aeruginosa cytotoxin contributes to the pathogenicity of the organism and that cytotoxin antibody is protective in a systemic P. aeruginosa infection in leukopenic mice.

Analysis of Variance↗
PubMed1994

New adhesives in Class V restorations under combined load and simulated dentinal fluid.

OBJECTIVES: This study compared the efficacy of three dentinal adhesives using the "all etch" technique (All-Bond 2, Bisco; Scotchbond MP,3M Dental Products Co.; OptiBond, Kerr) with a dentinal adhesive which still uses phosphoric acid to condition enamel and a self-etching primer for dentin (A.R.T.-Bond, Coltene/Whaledent). METHODS: Eight V-shaped mixed Class V restorations were placed per group in extracted human premolars. The restorations were subjected to 1,200,000 mechanical occlusal cycles (max. force 49 N; frequency 1.7 Hz) and 3,000 simultaneous thermal cycles (5-50-5 degrees C). Dentinal fluid was simulated using 1:3 diluted horse serum and fed into the pulp chamber both during restoration and loading. Percentages of "continuous margin" were assessed on SEM replicas of enamel and dentinal margins at 200x magnification immediately before and after stressing, respectively. RESULTS: No significant differences were observed before stress between the materials either in enamel or in dentin. After stress, however, OptiBond and A.R.T.-Bond performed significantly better in dentin than the two other adhesives (Kruskal-Wallis, Mann-Whitney; p < 0.05). Although high initial values were observed, All-Bond 2 and Scotchbond MP were not stress-resistant under simulated physiological conditions. SIGNIFICANCE: The predicted clinical potential of All-Bond 2 and Scotchbond MP is inferior to that of OptiBond and A.R.T.-Bond.

Acid Etching, Dental↗
PubMed1994

Effects of thermocycling and occlusal force on adhesive composite crowns.

The aim of this in vitro study was to provide first quantitative data on the marginal adaptation and the required load to fracture of adhesive composite crowns with and without adhesive composite cores. Eighteen caries-free extracted human premolars were restored using fine hybrid composite crowns with margins located entirely in dentin. Six crowns were adhesively luted to dentin stubs, six to endodontically treated teeth with adhesive titanium posts and adhesive composite cores, and six to adhesive composite cores without posts. Another ten unprepared teeth served as a control. All restored teeth were subjected to long-term occlusal and thermal stresses. The marginal adaptation was evaluated in the SEM before and after loading. Load to fracture was recorded at the end of the stress. Before stressing, 72.2 to 85.0%, and after stressing, 51.9 to 66.2% of "continuous margin" were recorded at the dentin-luting composite interface. The best results after stressing were achieved with crowns luted to adhesive composite cores without titanium posts. At the luting composite-composite crown interface, 61.6 to 88.7% of "continuous margin" before and 57.7 to 75.5% after stressing were recorded. The required load to fracture the restored teeth ranged from 72.0 to 89.2% of the unrestored, unloaded control. Adhesive composite cores without titanium posts yielded the best results.

Bite Force↗
PubMed1994

Scanning electron microscopic and clinical examination of composite resin inlays/onlays up to 12 months in situ.

In this limited clinical study, 30 posterior adhesive fine-particle hybrid composite resin inlays/onlays were placed. After 12 months in situ, 29 of the restorations were reexamined. The evaluation was carried out using clinical parameters and the scanning electron microscope. None of the restorations showed fractures, recurrent caries, or a clinically visible loss of substance. All restored teeth were vital. The radiopacity of the material was clinically sufficient. Only the color match, because of a suboptimal shade range, and the perfect removal of excess luting composite resin proved to be problematic. Furthermore, slight abrasion of the luting composite resin was observed, although the abrasion had no influence on the quality of the marginal adaptation. In the scanning electron microscope excellent marginal quality was observed initially (98.9% continuous margin) as well as after 12 months (94.9% continuous margin). The evaluated composite resin inlay/onlay system has proved to be reliable during 12 months in situ.

Adult↗
PubMed1994

[Amalgam as the measure in filling therapy. A determination of its place].

As the value of amalgam restorations is increasingly being questioned in modern dentistry, the clinical potential of amalgam restorations in general has been evaluated in this literature review. The major factors limiting the longevity of amalgam restorations are operator- and patient-related. Both factors will likewise influence the longevity of any new restorative concepts. Nevertheless, amalgam restorations remain the standard against which alternative materials are evaluated. Amalgam restorations are slowly loosing ground to the use of tooth-colored materials, which are gaining in popularity. However, amalgam can not currently be withdrawn from the list of possible restorative materials used for patients in Switzerland.

Costs and Cost Analysis↗
PubMed1994

[Clinical and long-term scanning electron microscopic studies of composite inlays].

24 composite inlays, which were thoroughly documented for postgraduate education purposes were recalled after 13.3 and 30.5 months on average. The clinical evaluation yielded very good results after 13.3 and good results after 30.5 months, respectively. Marginal gaps were observed in 6.6% at the tooth-composite cement and in 27.1% at the composite cement-inlay-interface after 13.3 months using replica technique and SEM. There values were not significantly different from the findings at 30.5 months. The adhesive failures between inlay and composite cement were preferably located in large, multisurfaced restorations. No significant differences were found between direct immediate inlays and lab-made indirect inlays and between molar and premolar restorations, respectively.

Composite Resins↗